The present invention relates to a valve device for use in suction/exhaust of a cylinder in an engine or an external combustion engine and a pump.
Conventional engines use a bevel valve, called a mushroom valve, as a valve for suction/exhaust of the cylinder, and, to establish timing between the rising/lowering movement of the piston and the opening/closing of the valve, interlocking the two elements with each other by means of gears, chains or cams.
The mushroom valve has a small valve opening area and is incapable of increasing the opening area in terms of its structure, so that when it is desired to improve the suction/exhaust efficiency to enable high-speed rotations, a plurality of mushroom valves needs to be provided, resulting in a complicated interlocking mechanism with the piston.
Additionally, in case of the valve device such as the mushroom valve for use in the conventional engine, the internal pressure acting on the valve disc is determined only by the area of the valve (the opening area of the valve seat, or the total area thereof when a plurality of valves are provided) irrespective of the cylinder diameter. For this reason, an increase in the valve area to improve the exhaust efficiency may induce an increase in the energy loss from opening the valve.
The crankcase compression type two-cycle engine makes use of the crankcase for scavenging, and hence has a poor scavenging efficiency, and requires mixing of a lubricant into fuel. This makes it difficult to solve the exhaust gas problems.
It is therefore a first object of the present invention to allow the suction/exhaust valve of the cylinder to be linked with motion of the piston without using any additional interlocking mechanism such as gears.
A second object of the present invention is to increase the valve area while minimizing the energy loss from opening the valve, to thereby enhance the intake/discharge efficiency for efficient operation.
A third object of the present invention is not to use the crankcase for scavenging, even in two-cycle engines, thereby eliminating the need to mix the lubricant and fuel, to obtain an improved exhaust gas.
A first embodiment of the invention provides an engine, having a valve device, the valve device comprising a cylinder into which a fluid is supplied, a piston mounted in the cylinder, and a valve for providing switching between suction and exhaust of a pressure fluid to and from the cylinder. The valve device comprises a valve seat defined by an opening for fluid inflow formed in an end face of the cylinder, the opening being smaller in area than the end face of the piston; and a valve disc arranged outside of the valve seat, the valve disc coming into abutment against the valve seat; wherein the cylinder is moveable in the axial direction, the end face of the cylinder capable of coming into or out of contact with the valve disc, wherein when the interior of the cylinder is pressurized as a result of abutment of the valve seat against the valve disc, the end face of the cylinder is urged toward the valve disc so that the valve seat and the valve disc are brought into press-contact with each other, and wherein the movement of the cylinder is controlled by the movement of the piston.
An engine, having a valve device, is configured such that the cylinder includes an upper cylinder and a lower cylinder, the upper cylinder being urged downward, the lower cylinder being urged upward, the lower cylinder having at its lower end a raised portion against which the lower end of the piston abuts, that when the piston rises, the lower cylinder also rises and thrusts up the upper cylinder to close the valve seat so that the valve seat comes into press-contact with the valve disc when the interior of the cylinder is pressurized, and that when the piston falls, the lower cylinder is disengaged from the upper cylinder so that an outlet is formed between the upper cylinder and the lower cylinder and that the valve seat is opened to form an opening.
It is to be noted that the engine intended for the present invention can include a pump, as well as the internal combustion engine and the external combustion engine.
The end face of the cylinder may be provided by an ordinary cylinder having an end face integrated with the cylinder body, or the cylinder can be of a type including a cylinder end face element that is fitted to an end portion of the cylinder body in such a manner that the cylinder end face element is movable along the central axis of the cylinder.
A second embodiment of the invention provides an engine, having a valve device, the valve device comprising a cylinder to which a fluid is supplied, a piston mounted in the cylinder, and a valve for providing switching between suction and exhaust of a pressure fluid to and from the cylinder, the valve device comprising a valve seat defined by an opening for fluid inflow formed in an end face of the cylinder, the opening being smaller in area than the end face of the piston; and a valve disc arranged outside of the valve seat, the valve disc coming into abutment against the valve seat, wherein
the cylinder is movable in its axial direction, the end face of the cylinder capable of coming into or out of contact with the valve disc, wherein
when the interior of the cylinder is pressurized as a result of abutment of the valve seat against the valve disc, the end face of the cylinder is urged toward the valve disc so that the valve seat and the valve disc are brought into press-contact with each other, and wherein the movement of the cylinder is controlled by the movement of the piston.
An engine, having a valve device, is configured such that above the cylinder are formed an inlet and an outlet, the inlet and the outlet each having a check valve, that the piston is urged upward by a piston spring, that the cylinder is urged upward by a cylinder spring, that the cylinder is provided at its lower end with a lock pin capable of being engaged with or disengaged from the cylinder for locking or unlocking the cylinder, the lock pin being controlled by an interlocking mechanism so as to come into or out of contact with the cylinder depending on the rotation of a crank, that the check valve of the outlet above the cylinder is opened for exhaust when the piston rises with the lock pin engaged with the cylinder, the check valve of the inlet being opened for introduction of new air when the piston falls with the lock pin engaged with the cylinder, and that combustion gas is emitted from the outlet above the cylinder when the piston falls with the lock pin disengaged from the cylinder.
A third embodiment of the invention provides an engine, having a valve device, the valve device comprising a cylinder into which a fluid is supplied, a piston mounted in the cylinder, and a valve for providing switching between suction and exhaust of a pressure fluid to and from the cylinder, the valve device comprising a valve seat defined by an opening for fluid inflow formed in an end face of the cylinder, the opening being smaller in area than the end face of the piston; and a valve disc arranged outside of the valve seat, the valve disc coming into abutment against the valve seat, wherein the cylinder is movable in its axial direction, the end face of the cylinder capable of coming into or out of contact with the valve disc, wherein when the interior of the cylinder is pressurized as a result of abutment of the valve seat against the valve disc, the end face of the cylinder is urged toward the valve disc so that the valve seat and the valve disc are brought into press-contact with each other, wherein the movement of the cylinder is controlled by the movement of the piston.
An engine, having a valve device, is configured such that the cylinder is urged upward by a cylinder spring, the cylinder having at its lower end a raised portion against which the lower end of the piston abuts, that a rotary valve is disposed between an inlet and an outlet above the cylinder, and that the rotary valve acts to provide a control such that both the inlet and the outlet are closed when the piston is at or in vicinity of its bottom dead center in a first cycle, the outlet being opened when the piston rises, the inlet being opened when the piston falls, and such that both the inlet and the outlet are closed all the time in a second cycle so that gas is emitted from an opening of the cylinder when the piston falls after ignition.
A fourth embodiment of the invention provides an engine, having a valve device, the valve device comprising a cylinder into which a fluid is supplied, a piston mounted in the cylinder, and a valve for providing switching between suction and exhaust of a pressure fluid to and from the cylinder, the valve device comprising a valve seat defined by an opening for fluid inflow formed in an end face of the cylinder, the opening being smaller in area than the end face of the piston; and a valve disc arranged outside of the valve seat, the valve disc coming into abutment against the valve seat, wherein the cylinder is movable in its axial direction, the end face of the cylinder capable of coming into or out of contact with the valve disc, wherein when the interior of the cylinder is pressurized as a result of abutment of the valve seat against the valve disc, the end face of the cylinder is urged toward the valve disc so that the valve seat and the valve disc are brought into press-contact with each other, and wherein the movement of the cylinder is controlled by the movement of the piston.
An engine, having a valve device, is configured such that above the cylinder are formed an inlet and an outlet, the inlet and the outlet each having a check valve, with an outlet for combustion gas being disposed below the outlet, the outlet for combustion gas being provided with a switching valve having an annular disc, that the switching valve is freely capable of rise and fall and is urged downward by a valve spring so as to come into abutment against the upper end of the cylinder, the switching valve closing the outlet for combustion gas when the switching valve falls, the switching valve closing the outlet above the cylinder when the switching valve rises, that the cylinder is provided with a lock pin capable of being engaged with or disengaged from the cylinder for locking or unlocking the cylinder, that in a first cycle, the cylinder is locked at its lower position by the lock pin, with the switching valve being pressed downward to close the outlet for combustion gas, and that in a second cycle, the cylinder is released from locking by the lock pint, with the switching valve being thrust upward by the pressure of the combustion gas when the piston falls after ignition so that the outlet for combustion gas is opened to emit combustion gas therethrough.
A fifth embodiment of the invention provides an engine, having a valve device, the valve device comprising a cylinder into which a fluid is supplied, a piston mounted in the cylinder, and a valve for providing switching between suction and exhaust of a pressure fluid to and from the cylinder, the valve device comprising a valve seat defined by an opening for fluid inflow formed in an end face of the cylinder, the opening being smaller in area than the end face of the piston; and a valve disc arranged outside of the valve seat, the valve disc coming into abutment against the valve seat, wherein the cylinder is movable in its axial direction, the end face of the cylinder capable of coming into or out of contact with the valve disc, wherein when the interior of the cylinder is pressurized as a result of abutment of the valve seat against the valve disc, the end face of the cylinder is urged toward the valve disc so that the valve seat and the valve disc are brought into press-contact with each other, and wherein the movement of the cylinder is controlled by the movement of the piston.
An engine, having a valve device, is configured such that above the cylinder are formed an inlet and an outlet, that the outlet is positioned such that the outlet is closed by the cylinder when the cylinder rises and that the outlet is opened when the cylinder falls, that an intermediate valve is disposed in such a manner as to be able to freely rise and fall between the cylinder and the valve disc, the intermediate valve having a bottom face coming into abutment against the valve seat of the cylinder and having a top face coming into abutment against the valve disc, the intermediate valve being urged downward by a valve spring, that when the piston is at its bottom dead center, an inlet flow passage is formed between the top face of the intermediate valve and the valve disc whilst an outlet flow passage is formed between the intermediate valve and the valve seat so that the interior of the cylinder is scavenged, that when the piston rises, the cylinder rises together with the rise of the piston and the intermediate valve comes into abutment against the valve seat to shut off fluid communication between a cylinder opening and the outlet to allow only inflow to continue, that when the cylinder further rises, the intermediate valve comes into abutment against the valve disc to close the cylinder opening, and that when the piston falls after combustion, the intermediate valve is thrust up by the pressure of combustion gas and the outlet flow passage is opened to emit combustion gas therethrough.
A sixth embodiment of the invention provides an engine, having a valve device, the valve device comprising a cylinder into which a fluid is supplied, a piston mounted in the cylinder, and a valve for providing switching between suction and exhaust of a pressure fluid to and from the cylinder, the valve device comprising a valve seat defined by an opening for fluid inflow formed in an end face of the cylinder, the opening being smaller in area than the end face of the piston; and a valve disc arranged outside of the valve seat, wherein an auxiliary valve disc is disposed in such a manner as to be able to freely rise and fall between an upper end face of the cylinder and the valve disc. The cylinder is movable in its axial direction, with the end face of the cylinder capable of coming into or out of contact with the auxiliary valve disc, wherein when the interior of the cylinder is pressurized as a result of abutment of the auxiliary valve disc against the valve seat and the valve disc, the end face of the cylinder is urged toward the valve disc so that the auxiliary valve disc is brought into press-contact with the valve seat and the valve disc, and wherein the movement of the cylinder is controlled by the movement of the piston.
An engine, having a valve device, is configured such that the engine body is provided with a seat for the auxiliary valve seat, that an inlet passage for thick gas mixture is disposed above the auxiliary valve disc, with an inlet passage for thin gas mixture being disposed below the auxiliary valve disc, that the auxiliary valve disc is provided with a vent for allowing the inlet passage for thick gas mixture to fluidly communicate with a cylinder opening, and that as a result of rise of the cylinder, the valve seat of the cylinder comes into abutment against and thrusts up the auxiliary valve disc so that the top face of the auxiliary valve disc is abutted against the valve disc so that the cylinder opening is closed to hermetically seal the interior of the cylinder.
A seventh embodiment of the invention provides an engine, having a valve device, according to any one of the previous six embodiments, wherein the valve disc is provided with a fuel injection nozzle and/or an igniter.
An eight embodiment of the invention provides an engine, having a valve device, the valve device comprising a cylinder into which a fluid is supplied, a piston mounted in the cylinder, and a valve for providing switching between suction and exhaust of a pressure fluid to and from the cylinder, the valve device comprising a valve seat defined by an opening for fluid inflow formed in an end face of the cylinder, the opening being smaller in area than the end face of the piston; and a valve disc arranged outside of the valve seat, the valve disc coming into abutment against the valve seat, wherein the cylinder is movable in its axial direction, the end face of the cylinder capable of coming into or out of contact with the valve disc, wherein when the interior of the cylinder is pressurized as a result of abutment of the valve seat against the valve disc, the end face of the cylinder is urged toward the valve disc so that the valve seat and the valve disc are brought into press-contact with each other, and wherein the movement of the cylinder is controlled by the movement of the piston.
An engine, having a valve device, is configured such that a cap of the engine body includes an inlet for pressure fluid, with between the inlet for pressure fluid and the valve seat of the cylinder there being provided, in such a manner as to be able to rise and fall, a valve disc for opening and closing a cylinder opening and a spherical auxiliary valve disc moving in conjugation with movement of the valve disc for opening and closing the inlet, that the cylinder and the valve disc are urged downward by respective springs, that the valve disc is provided with a communication passage for providing a communication between upper and lower portions so that when the valve disc rises, the auxiliary valve disc is thrust up by a protrusion to open the valve, that when the cylinder falls, the cylinder opening is opened to exhaust the interior of the cylinder of fluid whilst the valve seat at the inlet for pressure fluid is closed by the auxiliary valve disc, and that when the valve seat of the cylinder abuts against the valve disc, the opening is closed and the auxiliary valve disc is thrust up by the protrusion to open the inlet for pressure fluid so that the pressure fluid flows through the communication passage of the valve disc into the interior of the cylinder so that the piston is pressed down.
A ninth embodiment of the invention provides an engine, having a valve device, the valve device comprising a cylinder into which a fluid is supplied, a piston mounted in the cylinder, and a valve for providing switching between suction and exhaust of a pressure fluid to and from the cylinder, the valve device comprising a valve seat defined by an opening for fluid inflow formed in an end face of the cylinder, the opening being smaller in area than the end face of the piston; and a valve disc arranged outside of the valve seat, the valve disc coming into abutment against the valve seat, wherein the cylinder is movable in its axial direction, the end face of the cylinder capable of coming into or out of contact with the valve disc, wherein when the interior of the cylinder is pressurized as a result of abutment of the valve seat against the valve disc, the end face of the cylinder is urged toward the valve disc so that the valve seat and the valve disc are brought into press-contact with each other, and wherein the movement of the cylinder is controlled by the movement of the piston.
An engine, having a valve device, is configured such that a pump chamber is formed between an inner wall of an engine body and an outer wall of the cylinder capable of freely rising and falling, by differentiating in diameter the upper portion from the lower portion of the inner wall of the engine body via a shoulder and by differentiating in diameter the upper portion from the lower portion of the outer wall of the cylinder via a shoulder, that the pump chamber is placed in communication with a heater and a cooler, the heater leading to the upper portion of the cylinder, that between the inlet to the cylinder of the heater and the cylinder is disposed a valve disc for opening and closing a flow passage extending between the inlet and the cylinder by rise and fall of the piston, that the valve disc is in the shape of a tube with its upper portion having an opening which leads to the inlet, the valve disc being urged downward, that when the piston is at its top dead center, the valve disc is thrust up to allow the inlet and the valve disc opening to communicate with each other to open the flow passage whilst the valve disk opening and the outlet are closed to allow heated fluid to flow into the cylinder so that the piston is pressed down with the cylinder falling, and that when the cylinder falls, communication between the inlet and the cylinder is shut off and the cylinder is placed in communication-with the cooler by way of the outlet whilst the pump chamber is reduced in volume to allow fluid within the pump chamber to flow into the heater.
A tenth embodiment of the invention provides an engine, having a valve device, according to any one of the first through the fifth embodiments, wherein the cylinder is urged toward the valve disc, the cylinder being provided at its lower portion with a raised portion against which the lower end of the piston abuts, with a lower side wall of the cylinder having an outlet which opens when the piston falls, wherein between the piston and the lower portion of the cylinder is disposed a piston spring for urging the piston upward so that the piston closes the outlet when the piston spring has been fully extended, and wherein when the interior of the cylinder is pressurized as a result of rise of the piston, the valve seat comes into press-contact with the valve disc, whilst when the piston falls, the outlet is opened and the cylinder falls as a result of pressing by the piston so that the valve seat is disengaged from the valve disc.
An eleventh embodiment of the invention provides an engine, having a valve device, the valve device comprising a cylinder into which a fluid is supplied, a piston mounted in the cylinder, and a valve for providing switching between suction and exhaust of a pressure fluid to and from the cylinder, the valve device comprising a valve seat defined by an opening for fluid inflow formed in an end face of the cylinder, the opening being smaller in area than the end face of the piston; and a valve disc arranged outside of the valve seat, the valve disc coming into abutment against the valve seat, wherein the cylinder is movable in its axial direction, the end face of the cylinder capable of coming into or out of contact with the valve disc, wherein when the interior of the cylinder is pressurized as a result of abutment of the valve seat against the valve disc, the end face-of the cylinder is urged toward the valve disc so that the valve seat and the valve disc are brought into press-contact with each other, wherein the movement of the cylinder is controlled by the movement of the piston, wherein the cylinder consists of a cylinder body in the shape of a tube, and a cylinder end face element having an opening and a valve seat, the cylinder end face element being fitted to the upper end of the cylinder body in such a manner as to be able to rise and fall, wherein the cylinder body is firmly secured to the engine body, with the cylinder end face element being fitted to the cylinder body in an air-tight manner, the cylinder end face element being coupled to an actuator via a rod, and wherein the actuator is urged upward by a spring so that when the piston falls, the actuator falls as a result of pressing of the piston and that when the piston rises, the actuator rises by a biasing force of the spring.
The basic functions of the present invention will be described with reference to FIGS. 1 to 7 showing an application to the two-cycle engine.
As seen in FIG. 1, an engine 1 comprises a cylinder 3 positioned above a crankcase 2 in such a manner as to be able to rise and fall. The cylinder 3 is urged upward by a cylinder spring 4, with a piston 5 mounted within the cylinder 3. In the diagram, reference numeral 6 denotes a crank.
The cylinder 3 has in its upper end face an opening 7 for fluid inflow whose periphery defines a valve seat 8. Above the valve seat 8 is disposed a valve disc 9 that comes into abutment against the valve seat 8 when the cylinder 3 is in its rising stroke.
Between the upper end face of the cylinder 3 and the valve disc 9 is formed an inlet passage 10 which opens when the cylinder 3 is in its lowering stroke. The inlet passage 10 leads to the crankcase 2 by way of an inflow pipe 11 such that fresh air sucked from the inlet 12 of the crankcase 2 is supplied via the inlet passage 10 to the cylinder 3.
Reference numeral 13 denotes an outlet disposed at the lower portion of the cylinder 3.
FIG. 2 shows the state where the piston 5 is at its bottom dead center (0-degree crank angle). In this state, the lower end of the piston 5 abuts against a raised portion 14 formed on the lower end of the cylinder 3, and the cylinder 3 is pressed and moved downward by the piston 5. As a result, the valve seat 8 is disengaged from the valve disc 9 to allow fresh air to flow through the inlet passage 10 into the cylinder 3. Since the outlet 13 is also opened at that time, the residual gas within the cylinder is exhausted so that the interior of the cylinder 3 is filled with fresh air.
FIG. 3 shows the state of 60-degree crank angle, in which, attendant on the rise of the piston, the cylinder 3 rises by the spring force of the cylinder spring 4, and the valve seat 8 abuts against the valve seat 9 to close the opening 7, with the outlet 13 remaining opened.
FIG. 4 shows the state of 85-degree crank angle, in which the outlet 13 is closed by the piston so that the interior of the cylinder enters into the compression stroke.
In this compression stroke, the press-contact force between the valve seat 8 and the valve disc 9 will go up as the compression increases. Because the cylinder 3 is able to rise and fall, an upward force will act on the upper end face of the cylinder when the piston rises. Thus, the valve seat 8 comes into press-contact with the fixed valve disc 9.
For this reason, even though the opening 7 has a large area, any leakage of the fluid compressed within the cylinder can be prevented by means of a simple valve structure.
FIG. 5 shows the state of 180-degree crank angle, in which ignition is made near the piston top dead center. Although the piston lowers under pressure generated by ignited and burned gas, an upward force acts on the cylinder as described above so that the valve seat keeps press-contact with the valve disc. The opening 7 remains open until the cylinder is pressed down by the piston when the combustion gas is discharged attendant on opening of the outlet 13 as a result of further descent of the piston (FIG. 6 depicting the state of 280-degree crank angle).
FIG. 7 shows the state of 315-degree crank angle, in which the piston 5 abuts against the raised portion 14 at the bottom of the cylinder 3 to press down the cylinder. At that time, the valve seat 8 is disengaged from the valve disc 9 to open the opening 7, into which fresh air compressed in the crankcase flows, returning to the state of FIG. 2.
FIGS. 8 to 11 illustrate an example of application to a two-cycle engine.
As shown in FIG. 8, the engine generally designated at 1 comprises a cylinder 3 capable of rising and lowering, disposed above a crankcase 2. The cylinder 3 is urged upward by a cylinder spring 4. The lower end of the cylinder 3 comes into abutment against a raised portion 15 of the engine body upon the fall so that the cylinder 3 can lower to a limit required to open an outlet 13. A piston 5 is mounted within the cylinder 3 and is biased upward by a piston spring 16 which is supported on the lower end of the cylinder 3. In the diagram, reference numeral 6 denotes a crank.
An opening 7 is formed in the upper end face of the cylinder 3 so that a valve seat 8 is defined by the periphery 2o of the opening 7. Above the valve seat 8 is disposed a valve disc 9 which comes into abutment against the valve seat 8 when the cylinder 3 rises.
Between the upper end face of the cylinder 3 and the valve disc 9 is formed an inlet passage 10 which is opened when the cylinder 3 lowers. The inlet passage 10 leads via an inflow pipe 11 to the crankcase 2 such that fresh air sucked through an inlet 12 of the crankcase 2 is fed to the cylinder 3 by way of the inlet passage 10.
The piston spring 16 has a larger spring force than the cylinder spring 4 to ensure that the piston 5 closes the outlet 13 when the piston spring 16 has fully been stretched.
FIG. 8 illustrates the piston 5 located at its bottom dead center (crank angle of 0 degrees). In this state, the piston spring 16 is compressed, and the cylinder 3 is pressed and lowered by the piston 5, with the valve seat 8 and the valve disc 9 being separated from each other. Thus, fresh air flows through the inlet passage 10 into the cylinder 3 whilst resilient gas within the cylinder 3 is exhausted through the opened outlet 13, whereupon the interior of the cylinder 3 is filled with fresh air.
FIG. 9 illustrates the state of a 60-degree crank angle. In this state, the piston 5 rises but the cylinder 3 is pressed so as not to rise by a spring force of the piston spring 16. As a result, the opening 7 remains open and the outlet 13 is blocked by piston 5. Accordingly, inflow of fresh air continues after the blocking of the outlet 13 so that a so-called inertia super charging is performed.
FIG. 10 illustrates the state of an 85-degree crank angle. In this state, when the piston 5 further rises and the piston spring 16 is extended, the spring force of the cylinder spring 4 overcomes the spring force of the piston spring 16, allowing a rise of the cylinder 3 so that the valve seat 8 comes into abutment against the valve disc 9 to block the opening 7. The interior of the cylinder thus enters into the compression stroke.
In this compression stroke, the press-contact force between the valve seat 8 and the valve disc 9 increases as the compression increases. That is, the cylinder 3 is able to rise and, upon the rising of the piston, an upward force is applied to the upper end face of the cylinder. Thus, the valve seat 8 can come into press-contact wit the fixed valve disc 9.
This enables any leakage to be prevented with a simple valve structure in spite of a larger area of the opening 7.
FIG. 11 illustrates the state of a 180-degree crank angle where an ignition is carried out in the vicinity of the top dead center of the piston. The piston is lowered by pressure generated by the ignited and burned gas, whereas the cylinder is subjected to the upward force as described above so that the press-contact state is kept between the valve seat and the valve disc. The opening 7 remains closed until the piston is further lowered to open the outlet 13 for exhaust of the combustion gas, with the result that the cylinder is pressed down by the piston.
A further lowering of the piston 5 allows the lower end of the cylinder 3 pressed down by the piston spring 16 to come into abutment against the raised portion 15 of the body, so that the piston 5 lowers while compressing the piston spring 16, returning to the state of FIG. 8.
In the compression stroke, since the area of the opening 7 is smaller than the plane area of the piston 5, an axial force applied on the cylinder, corresponding to the difference in area, works in the direction pressing the valve, and the axial force is combined with the upward force obtained from a difference in spring force between the cylinder spring 4 and the piston spring 16. Hence, as the cylinder internal pressure goes up, the press-contact force between the valve seat and the valve disc increases so that the pressures of the compressed air and next combustion gas cannot leak out to the exterior.
In the above embodiment, only the piston 5 rises while pressing down the cylinder 3 under the action of the piston spring 16, whereupon inflow can continue with the outlet 13 closed as seen in FIG. 9, thus achieving the improved inflow efficiency.